3.—(1) For the purposes of this Order a person is a member of another’s family if—
(a)he is the spouse of that person, or he and that person live together as husband and wife, or
(b)he is that person’s parent, grandparent, child, grandchild, brother or sister.
(2) For the purpose of paragraph (1)(b)—
(a)a relationship by marriage shall be treated as a relationship by blood,
(b)a relationship of the half-blood shall be treated as a relationship of the whole blood, and
(c)the stepchild of a person shall be treated as his child.